Angie Drobnic Holan is an editor at Politifact, which weighs in on the truth or fibbery of politicians and pundits. I generally find them and most of the fact-checking sites fair and accurate, even when they proclaim my guy or gal a liar. Once in a while, I think they treat awkward phrasing as deliberate prevarication but generally, they're even-handed.
Ah, but one thing bothers me about these enterprises. I think they need to do a better job of not letting people reduce their findings to "Politician X was caught lying 78% of the time whereas Politician Y only lies 31% of the time." Their scoring has a lot to do with which statements they choose to check. Donald Trump's rating could go up or down depending on which of his more arguable statements they scrutinize. They point this out but then they do charts like the one in the linked article that makes it easy to overlook the selectivity of the process.